"""
Configuration management for tddai.

The tddai framework is project-agnostic and can be configured per project
via environment variables:

- TDDAI_WORKSPACE_DIR: Workspace directory name (default: .tddai_workspace)
- TDDAI_GITEA_URL: Git platform URL
- TDDAI_REPO_OWNER: Repository owner/organization
- TDDAI_REPO_NAME: Repository name

Example .env file for a project:
```
TDDAI_WORKSPACE_DIR=.myproject_workspace
TDDAI_GITEA_URL=https://github.com
TDDAI_REPO_OWNER=myusername
TDDAI_REPO_NAME=myproject
```
"""

import os
from pathlib import Path
from typing import Optional
from dataclasses import dataclass

from .exceptions import ConfigurationError


def load_dotenv_file(env_file: Path) -> None:
    """Load environment variables from a .env file."""
    if not env_file.exists():
        return

    with open(env_file, 'r') as f:
        for line in f:
            line = line.strip()
            if line and not line.startswith('#') and '=' in line:
                key, value = line.split('=', 1)
                os.environ.setdefault(key.strip(), value.strip())


@dataclass
class TddaiConfig:
    """Configuration settings for tddai."""

    # Workspace settings
    workspace_dir: Path = Path(".tddai_workspace")
    current_issue_file: str = "current_issue.json"

    # Git repository settings (must be configured per project)
    gitea_url: str = ""
    repo_owner: str = ""
    repo_name: str = ""

    # Test settings
    tests_dir: Path = Path("tests")
    test_file_pattern: str = "test_issue_{issue_num}_{scenario}.py"

    # AI settings
    claude_code_command: str = "claude"

    @property
    def issues_api_url(self) -> str:
        """Get the full issues API URL."""
        return f"{self.gitea_url}/api/v1/repos/{self.repo_owner}/{self.repo_name}/issues"

    @property
    def current_issue_path(self) -> Path:
        """Get the path to current issue file."""
        return self.workspace_dir / self.current_issue_file

    @classmethod
    def from_environment(cls) -> "TddaiConfig":
        """Create config from environment variables and .env files."""
        # Auto-load .env.tddai file if it exists
        env_file = Path(".env.tddai")
        load_dotenv_file(env_file)

        config = cls()

        # Override with environment variables if present
        gitea_url = os.getenv("TDDAI_GITEA_URL")
        if gitea_url:
            config.gitea_url = gitea_url

        repo_owner = os.getenv("TDDAI_REPO_OWNER")
        if repo_owner:
            config.repo_owner = repo_owner

        repo_name = os.getenv("TDDAI_REPO_NAME")
        if repo_name:
            config.repo_name = repo_name

        workspace_dir = os.getenv("TDDAI_WORKSPACE_DIR")
        if workspace_dir:
            config.workspace_dir = Path(workspace_dir)

        return config

    def validate(self) -> None:
        """Validate configuration settings."""
        if not self.gitea_url:
            raise ConfigurationError("gitea_url cannot be empty")

        if not self.repo_owner:
            raise ConfigurationError("repo_owner cannot be empty")

        if not self.repo_name:
            raise ConfigurationError("repo_name cannot be empty")


# Global config instance
_config: Optional[TddaiConfig] = None


def get_config() -> TddaiConfig:
    """Get the global configuration instance."""
    global _config
    if _config is None:
        _config = TddaiConfig.from_environment()
        _config.validate()
    return _config


def set_config(config: TddaiConfig) -> None:
    """Set the global configuration instance."""
    global _config
    config.validate()
    _config = config